Calculation Of The Moho Depth And The Lithosphere Effective Elastic Thickness Of Canada Basin And Its Adjacent Areas

The expansion process of Canada Basin and its adjacent areas,in Arctic Ocean,is complicated.Its western and northern parts are respectively affected by the chukchi marginal collision and the volcanic activity of the alpha-mendeleev ridge,which are the focus of current scholars.The moho depth records the dynamics of the earth's crust,which is the key evidence for understanding the evolution of the earth.The Effective Elastic Thickness(Te)of the lithosphere,as a parameter to characterize lithosphere strength,represents lithosphere's resistance to bending deformation under long-term(>105 years)load.It is very significant to study the effective elastic thickness of lithosphere for understanding the evolution of complex lithosphere.Therfore,we calculate the moho depths and Te of this region.And then we discuss its deep structural characteristics and further analyzes its dynamic evolution process in the Canada basin and its adjacent area.In this thesis,the free-air gravity anomaly is firstly corrected to obtain the mantle gravity anomaly.Then,we inverse the moho depth of the study areas by Parker method combining with the control points.The results show that the depth value increases gradually from west to east,which consistented with the trend of Glebovsky's 3D crustal model of the arctic region.The moho depth of the Canada Basin is between 15 and 20km,the deepest in Mackenzie delta is about 32km,the moho depth of Chukchi borderland is about 20km,and the shallow depth of the transition zone is about 13km,which coincides with the phenomenon of clockwise subduction and collision at the borderland.The crust in the study area is gradually transited from continent to transitional zone to ocean.Meanwhile,the Effective Elastic Thickness of the lithosphere in the study area was obtained by Moving Windows Admittance Method(MWAM)based on topography and gravity anomaly data of the Canada basin and its adjacent areas.Using Multitaper method to calculate the power spectral density.The window size of 400km×400km-1000km×1000km with an interval of 200km is adopted,and the weighted average of five windows is taken as the final result of the study area.The results showed that the Te in the study area was 30-70km,among which the Te value in the middle of the sea basin was mostly 40-50km,and there was no obvious symmetrical distribution feature.It can be seen that there is a clear boundary between Te at the position of about 140°W,with large Te value in the west and small Te value in the east,indicating weak lithosphere strength in the east.